The referenced prior patent application discloses a domestic boiler having a refractory lined firebox and grate, an overhead front-to-back sliding and removable boiler module having vertical fire tubes and a surrounding water chamber, and a removable ash drawer at the bottom of the boiler. The rectangular boiler included a thermally insulated wall, and appropriate supports, guides and fasteners were provided for internal components of the boiler.
While the boiler in the prior application proved perfectly sound from the standpoint of operational efficiency and convenience of use, it left something to be desired in terms of compatibility with mass production techniques and was particularly lacking in ease of assembly because of the necessity for installation of certain fasteners and somewhat difficult welding procedures on a mass production basis.
The objective of the present invention is to improve on and simplify the boiler in accordance with the prior application, most particularly in terms of facilitating its assembly and completely eliminating the necessity for bolting internal components. In accordance with a key feature of the invention, certain side protectors used within the boiler are merely dropped into place with previously inserted front and back protectors and serve therewith to position and retain the proper number of fire bricks along each side of the boiler, the latter being further stabilized and positioned by a flat grate at the bottom of the fire box resting on primary welded support flanges. The drop-in side protectors also form horizontal guide rails for the slide-in, slide-out boiler power module and a strong and positive easily releasable clamping retainer means for this module is included on the back wall of the boiler. All key parts are easily installed and removed through the back wall opening which receives the slide-in, slide-out module. The front, back and side protectors which drop easily into place in the boiler shell also interfit to position one another and to positively confine the fire bricks in the front-to-back direction.
A very important feature of the invention is that the boiler side protectors become the key to establishing and changing boiler size. The length of the boiler is increased front-to-back by adding side protectors and additional fire bricks, as desired. The structure is highly practical from a manufacturing and ease of assembling standpoint, is very sturdy and comparatively low cost. The internal protectors can be cast iron or molded refractory material, or a combination of such material, with suitable cast iron inserts.
Another significant improvement feature over the structure in the referenced application is the provision in the boiler of a built-in easily operated scraper for the top of the boiler module and a convenient portable boiler tube cleaner.
Other objects and advantages of the invention will become apparent during the course of the following description.